Kurumi was Ichiko's best friend in grade school. Ichiko and Kurumi were in love with Yusuke who received from both of them a chocolate. But the only one who received back a chocolate was Ichiko and he gave her a kitty accessory for her hat. Kurumi knew, it was from Yusuke and wanted the accessory, so she threatened Ichiko not to speak with her anymore. Ichiko didn't want to end their "friendship" so she had no other choice than to give it to Kurumi. Then Kurumi confessed to Yusuke but got rejected. She told Yusuke that Ichiko gave her the accessory because it didn't mean anything to her. Yusuke got angry at Ichiko and didn't want to talk with her anymore. Kurumi started badmouthing Ichiko and that's why Ichiko wasn't able to trust or to get close to anyone.